1. Field of the Invention
This invention relates to novel amidinium compounds and is more particularly concerned with amidinium carboxylate salts and their use as catalysts in the polymerization of organic isocyanates.
2. Description of the Prior Art
Amidines in general are strongly basic compounds which are known to react with acids to form amidinium salts such as chlorides, sulfates, acetates, and the like. For a comprehensive review of amidinium salts and their chemistry see "Advances in Organic Chemistry Methods and Results" Vol. 9 Iminium Salts in Organic Chemistry Part 2, p 321 et seq, 1979, John Wiley and Sons, New York, N.Y.
The reported amidinium carboxylate salts are those of the simple unsubstituted amidines as generally disclosed in "The Organic Chemistry of Nitrogen" by N. V. Sidgwick revised by Taylor et al, p 156, 1942, Oxford University Press, New York, N.Y. and typically, acetamidine acetate (see Taylor et al, J. Am. Chem. Soc. 82, 3138-3141 [1960]). Also, certain N,N'-disubstituted formamidinium and acetamidinium acetates have been reported by Taylor et al, J. Org. Chem. 28, 1108 (1963).
The N,N,N',N'-tetrasubstituted amidinium salts which have been reported to date have included particular halide, perchlorate, picrate, hexafluorophosphate derivatives but not carboxylates; see "Advances in Organic Chemistry" Part 2 cited supra and D. H. Clemens et al, J. Org. Chem. 29, 2932-2936, 1964.
I have now discovered what I believe to be a novel class of N,N,N',N'-tetrasubstituted amidinium carboxylate salts which find particular utility in catalyzing the polymerization of organic polyisocyanates.